In conventional practice a semi-tractor is drivingly connected to a trailer with a fifth wheel coupling including a kingpin attached to the trailer and a receiver that is bolted to the frame of the semi-tractor. The coupling is semi-rigid with limited lost motion, and the tractor essentially must have sufficient power to initiate movement of the entire weight of the trailer and load. Various efforts have been made in the transportation industry to improve energy conversion efficiency and reduce frictional losses such as rolling resistance, but the improvements continue to be incremental in nature, and the overall rates of fuel consumption and combustion emission production remain unacceptably high. Accordingly, what is needed is a semi-tractor/trailer load coupling that allows the tractor to initiate movement of the trailer and its load with reduced effort, leading to corresponding reductions in fuel consumption and combustion emission production.